Study On The Landslide Monitoring Sequence Algorithm Of BDS-3/GNSS Complex Environment

Global navigation satellite system(GNSS)is widely used in Deformation monitoring of landslides,bridges,slopes,etc.because it can provide low-cost and high-precision real-time three-dimensional position.However,in complex environments such as landslides,due to the influence of factors such as alpine vegetation shielding,GNSS signals are very vulnerable to multi-path effects,and deformation sequences will have problems such as discontinuous monitoring,many outlier,and large deformation fluctuations,making it difficult to obtain reliable monitoring results.In view of the above problems,this paper carried out the performance analysis of BDS-3 B1C/B2 a against multipath interference,demonstrated the PPP and RTK monitoring performance of BDS-3 in complex environment,studied the key technologies such as segmented environment modeling theory,dual frequency multipath correction method,robust adaptive estimation and BDS-3 sidereal day filtering,and carried out verification analysis in typical landslide scenarios.The main work and achievements of this article are as follows:(1)Analyzed and evaluated the characteristics of BDS-3 application in complex landslide monitoring environments.Firstly,the anti multipath performance of BDS-3 new signal in complex environments was studied and analyzed,and then PPP and RTK positioning performance analysis was conducted based on landslide measurement data.The results show that in complex environments,the B1C/B2 a multipath anti-interference ability and positioning performance of BDS-3 are better than those of B1I/B3 I frequency points,and are comparable to the L1/L2 frequency points of GPS.The monitoring accuracy of BDS-3combined with GPS RTK is 30% higher than that of a single GPS system.(2)In response to the problem of poor GNSS data quality caused by multipath effects in complex landslide environments,an adaptive segmented environment model(segmentation method)suitable for mountain occlusion is proposed based on the terrain feature cut-off height angle model,by evaluating the multipath and signal-to-noise ratio information of the monitoring station observation environment.Secondly,in response to the environment of bridge occlusion and severe ground reflection,a quality control correction algorithm(correction method)is proposed based on the correlation characteristics of dual frequency multipath information between the monitoring station and the reference station,taking into account the common information of dual frequency multipath between the reference station and the monitoring station.Comprehensive verification was conducted using monitoring data from the North Grottoes,Gansu Road and Bridge,and Heifangtai landslides.The results show that both the segmentation method and the correction method can effectively eliminate observations affected by occlusion,with the correction method having a better effect,with a fixed ambiguity rate of 98.3%,an increase of 27.3% compared to the fixed cutoff angle model,and an increase of 8.1% compared to the segmentation method.(3)Aiming at the problems of poor continuity of landslide displacement sequence and many outlier,an adaptive equal weight robust factor method is proposed by improving IGGIII weight function.On this basis,in view of the problem that high-precision stable landslide monitoring sequence cannot be obtained under the environment of severe multi-path interference,taking into account the average orbital period of navigation satellites,a sidereal day filtering algorithm taking into account the BDS-3 orbital period is proposed,Compared to the EMD filtering method in the coordinate domain,it increases by 33%,and compared to the wavelet filtering method in the coordinate domain,it increases by 40%.